Research in the last few decades has led to many developments related to terahertz (millimeter wave) technologies. The terahertz bandwidth is the frequency range of 100 GHz (0.1 THz) to 30 THz and is situated between the two established frontiers: the microwave and infrared spectral bands. The terahertz bandwidth has not been extensively utilized due to the insufficiency of the associated technology and other scientific constraints. Advancements in femtosecond laser technology, coherent generation, and detection have made the terahertz spectral window accessible to numerous applications and fundamental studies, like imaging, communications, explosive detection, spectroscopy of molecular vibrations, control of spin, and lattice vibrations.
Efficient terahertz devices are required for an active utilization of the terahertz regime. Modulators that can be dynamically tuned are the fundamental components of numerous devices and applications in telecommunication and wave processing systems, such as phased array antennas, isolators, filters, absorbers, frequency shifters, spectral lensing, amplifiers, and lasers. Attempts have been made to develop an efficient design of modulators for terahertz applications, but they are burdened with some inherent drawbacks, such as the need of cryogenic temperature for operation, insufficient speeds of operation, and modulation only up to a few percent.
Most of the approaches reported so far primarily rely on metamaterial resonance to overcome these limitations. Exploitation of natural materials, however, has yet to be effectively studied in this context.
The drawings illustrate only example embodiments and are therefore not to be considered limiting of the scope described herein, as other equally effective embodiments are within the scope and spirit of this disclosure. The elements and features shown in the drawings are not necessarily drawn to scale, emphasis instead being placed upon clearly illustrating the principles of the embodiments. Additionally, certain dimensions may be exaggerated to help visually convey certain principles. In the drawings, similar reference numerals between figures designate like or corresponding, but not necessarily the same, elements.